JP4562401B2 - Surface coated cutting tool - Google Patents

Description

  The present invention relates to a surface-coated cutting tool in which a hard coating layer having improved chipping resistance and film peel resistance and improved interlayer adhesion is formed on the surface and a method for producing the same, and particularly to a black skin and a hard particle phase. The present invention relates to a surface-coated cutting tool having excellent cutting characteristics when cutting difficult-to-cut materials such as cast iron containing iron and a method for manufacturing the same.

Conventionally, a cutting tool widely used for metal cutting is a hard phase mainly composed of at least one of the periodic table 4a, 5a, and 6a group metals, particularly WC (tungsten carbide), and Co (cobalt). A hard coating layer such as a TiC layer, a TiN layer, a TiCN layer, and an Al ₂ O ₃ layer is formed on the surface of a hard alloy such as a cemented carbide or a cermet made of a binder phase of an iron group metal such as Ni or nickel. Alternatively, a surface-coated cutting tool having a plurality of layers formed thereon is used, and among them, a cutting tool that is sequentially formed in the order of a combination of TiC layer, TiN layer and TiCN layer (titanium-based coating layer) -aluminum oxide layer is frequently used. Yes.

  These surface-coated cutting tools are mainly used for cutting cast iron, carbon steel, etc., but peeling between hard-coated layers due to low interlaminar adhesion between the titanium-based hard layer and the aluminum oxide layer of the hard-coated layer. There was a problem that chipping occurred and the wear resistance of the cutting tool was lowered.

  Therefore, in Patent Document 1, after forming a titanium-based hard layer including a TiCN layer, a heat treatment is performed in a hydrogen atmosphere of 10 to 100 torr at a temperature of 850 to 1100 ° C. for 1 to 5 hours. W and Co are diffused into the crystal grain boundaries to improve the interlayer adhesion of the hard layer.

In Patent Document 2, the maximum diffraction peak height is obtained at a diffraction angle (2θ) of 24.0 ± 1 degree by X-ray diffraction using a Cukα ray as a radiation source between a TiCN layer and an Al ₂ O ₃ layer. By interposing a chemical vapor deposition or physical vapor deposition Ti ₂ O ₃ layer showing an X-ray diffraction pattern with an average layer thickness of 0.1 to 2 μm, the interlayer adhesion between the TiCN layer and the Al ₂ O ₃ layer is improved. ing.
Japanese Patent No. 3269305 JP-A-11-269650

  However, in the method disclosed in Patent Document 1, the adhesion between the titanium-based hard layer and the aluminum oxide layer is not sufficient particularly when cutting a work material that requires impact resistance such as cast iron. there were.

Moreover, the method of interposing a titanium oxide between the TiCN layer and the Al ₂ O ₃ layer disclosed in Patent Document 2 cannot cope with recent high-load processing.

  Accordingly, the present invention has been made to solve the above-mentioned problems, and its purpose is particularly in the case of cutting under severe conditions when cutting difficult-to-cut materials such as cast iron containing black skin and hard particle phase. Another object of the present invention is to provide a long-life cutting tool having excellent wear resistance by preventing peeling and chipping of a hard coating layer during cutting.

  As a result of studying the above problems, the inventor has a single layer and / or multiple layers of titanium nitride, carbide, carbonitride, carbonitride on the surface of the tungsten carbide base cemented carbide base material. The presence of the second layer containing at least Al, Ti, W, and Co between the first layer and the third layer made of aluminum oxide makes it possible to use titanium nitride, carbide, carbonitride, carbonitride. As a result of improving the interlayer adhesion between the first layer consisting of layers and / or multiple layers and the third layer consisting of aluminum oxide and between the base material and the first layer, the adhesion strength of the hard coating layer is improved, It was found that chipping and film peeling during cutting can be suppressed.

  The second layer is preferably formed by diffusing any element in the base material, the first layer, and the third layer.

Furthermore, it is important that the average film thickness is 0.05 to 4 μm when it is assumed that the second layer exists intermittently and the second layer exists continuously and uniformly.

In the Auger electron spectroscopic analysis data for the second layer, the peak intensity of Al near 1400 eV, the peak intensity of W near 1750 eV, and the peak intensity of Co near 800 eV are I _Al , I _W , and I _Co , respectively. Sometimes, it is desirable that I _W / I _Al = 0.1 to 0.5 and I _Co / I _Al = 0.1 to 0.5.

  Furthermore, it is desirable that the uppermost layer of the first layers is composed of a streaky titanium carbonitride layer.

  Moreover, it is desirable that the average thickness of the streaky titanium carbonitride layer be 0.5 to 15 μm.

  Furthermore, it is desirable that the lowermost layer of the first layer is composed of a granular titanium nitride layer.

  The average thickness of the titanium nitride layer is preferably 0.5 to 3 μm.

  Furthermore, it is desirable that the aluminum oxide of the third layer is a κ-type crystal or a mixed crystal in which the κ-type crystal accounts for 50% by weight or more and the remainder is an α-type crystal.

  In addition, it is desirable that the W and Co concentrations on the extreme surface of the tungsten carbide-based cemented carbide base material be higher than those in the base material.

  Furthermore, it is desirable that the W and Co concentrations in the second layer are at least twice as high as the W and Co concentrations in the first layer and the third layer.

  According to the surface-coated cutting tool according to the present invention, between the first layer made of titanium nitride, carbide, carbonitride, carbonitride, and / or the third layer made of aluminum oxide. By the presence of a second layer containing at least Al, Ti, W, and Co, the first layer consisting of a single layer or multiple layers of titanium nitride, carbide, carbonitride, carbonitride and aluminum oxide It is possible to improve interlayer adhesion between the third layers, and to suppress tool damage such as chipping and film peeling during cutting.

  In addition, according to the method for manufacturing a surface-coated cutting tool according to the present invention, a single layer or multiple layers of titanium nitride, carbide, carbonitride, and carbonitride are formed on the surface of the tungsten carbide base cemented carbide base material. After sequentially forming a first layer composed of a layer and a third hard layer composed of aluminum oxide, in a hydrogen and / or nitrogen atmosphere of 1.3 to 40 kPa, a treatment temperature: 850 to 1100 ° C. and 1 to 10 By performing heat treatment for a time, a second layer mainly containing titanium (Ti), aluminum (Al), tungsten (W), and cobalt (Co) is formed between the first layer and the third layer. Interlayer adhesion between the first layer composed of a single layer or multiple layers of titanium nitride, carbide, carbonitride, carbonitride and the third layer composed of aluminum oxide can be easily improved. , Chip in cutting The tool damage packaging and film peeling can be easily suppressed.

  FIG. 1, which is a conceptual diagram of an example of the surface-coated cutting tool of the present invention, FIG. 2, which is a schematic enlarged sectional view of the main part and the vicinity of the second layer in FIG. 1, Description will be made based on FIG. 3 which is a schematic enlarged cross-sectional view of the main part about the interface and FIG. 4 which shows the results of Auger electron spectroscopy analysis of the second layer 3.

  According to FIG. 1, the surface-coated cutting tool of the present invention comprises a single layer and / or multiple layers of titanium nitride, carbide, carbonitride, carbonitride on a tungsten carbide base cemented carbide base material 1. A hard coating layer 1 formed by sequentially forming a first layer 2 and a third layer 4 made of aluminum oxide.

  In the present invention, the second layer 3 containing at least titanium (Ti), aluminum (Al), tungsten (W), and cobalt (Co) exists between the first layer 2 and the third layer 4. This second layer 3 serves as an intermediate layer, improves the interlayer adhesion between the first layer 2 and the third layer 4, increases the adhesion strength of the hard coating layer 1, The effect which suppresses the fall of cutting performance, such as abrasion resistance by chipping and film | membrane peeling, can be acquired.

  Here, according to the present invention, the second layer 3 is preferably formed by diffusion of an element contained in any of the base material 6, the first layer 2, and the third layer 4. Since the elements of the first layer 2 and the third layer 4 are contained in the second layer 3 by diffusion, the interlayer adhesion between the second layer 3 and the first layer 2 and between the second layer 3 and the third layer 4 is improved. This is desirable because it improves the film peeling resistance. Furthermore, since W and Co which are elements in the base material 6 are contained, the interlayer adhesion and toughness of the second layer 3 are improved, so that the chipping resistance and chipping resistance are also improved.

Further, since the second layer 3 is intermittently present, the residual stress applied to the hard coating layer 1 can be optimized, which is desirable in terms of preventing film peeling and chipping due to the residual stress. Here, the intermittent presence means that the intermittent portions 10 are scattered in the second layer 3 as shown in FIG. Further, when it is assumed that the second layer 3 is continuous and uniform (assuming that the corners of the intermittent portions are connected linearly), the average film thickness of the second layer 3 is 0. it is 05~4μm is a first layer 2 can improve the adhesion of the third layer 4, and is important because it is possible to prevent a decrease in adhesion due to thickening.

As shown in FIG. 4, in the Auger electron spectroscopic analysis data for the second layer 3, the peak intensity of Al near 1400 eV, the peak intensity of W near 1750 eV, and the peak intensity of Co near 800 eV are respectively expressed as I _Al , When I _W and I _Co are used, the ratio of I _W / I _Al is 0.1 to 0.5, and the ratio of I _Co / I _Al is 0.1 to 0.5. This is desirable because it can be prevented from diffusing to become a source of destruction and can improve the fracture resistance.

  Further, the aluminum oxide of the third layer 4 is a κ-type crystal, or the κ-type crystal accounts for 50% by weight or more, and the remainder is a mixed crystal made of α-type crystal, which is a high load such as cast iron black skin cutting. In cutting, it is desirable that the interlaminar adhesion with the second layer 3 can be further improved, thereby improving the film peeling resistance of the third layer 4 made of aluminum oxide. These crystal structures can be measured by a general X-ray diffraction method (not shown). Here, in the third layer 4 made of aluminum oxide, compounds such as Ti carbide, oxide, nitride, carbonitride, carbonate and carbonitride are contained by diffusion during the heat treatment described later. It may be.

  In addition, it is desirable that the uppermost layer 8 of the first layer 2 is made of titanium carbonitride composed of streak-like particles, since the fracture resistance can be improved without deteriorating the wear resistance. Furthermore, when the average film thickness of the titanium carbonitride layer is 0.5 to 15 μm, particularly 4 to 8 μm, the toughness of the third layer 4 can be improved, and the adhesive force is reduced due to the thick film. This is desirable because it can be prevented.

  Further, as shown in FIG. 3, the inclusion of the underlayer 7 made of granular titanium nitride as the first layer improves the interlayer adhesion between the base material 6 and the first layer 2, and the first layer 2 and the first layer 2 Due to a synergistic effect with the effect of improving the interlayer adhesion of the three layers 4, high load cutting such as cast iron black skin cutting is desirable in terms of further improving film peeling resistance and chipping resistance. Further, since the diffusion amount of WC and Co from the base material can be adjusted by titanium nitride, the film thickness of the second layer 3 can be controlled, and the hard coating layer due to excessive diffusion of WC and Co 1 can be prevented from being deteriorated.

  Further, the average film thickness of the underlayer 7 is 0.5 to 3.0 μm, it is possible to improve the adhesion of the third layer 4, improve the film peeling resistance and chipping resistance, and This is desirable because it can prevent a reduction in adhesion due to thickening.

  Furthermore, the extreme surface of the tungsten carbide base cemented carbide base material 6, in particular, the concentration of W and Co in the depth range of 0.05 to 3 μm from the surface to the inside is higher than the inside. This is desirable because it can absorb the impact generated during the process and improve the fracture resistance of the hard coating layer 1.

  Further, the W and Co concentrations contained in the second layer 3 are more than twice as high as the W and Co concentrations contained in the first layer 2 and the third layer 4, preferably , WC and Co are not detected in the first layer 2 and the third layer 4 at 1 wt% or less, particularly 0.5 wt% or less, and are detected only in the second layer. It is desirable because the interlayer adhesion of the three layers can be strengthened and the wear resistance of the hard coating layer 1 can be prevented from being lowered.

  Moreover, it is desirable to attach TiN as the outermost layer 5 of the hard coating layer 1. Since TiN has a gold color, TiN wears after cutting, and the color of the worn part is not gold, so it is possible to determine whether or not the surface-coated cutting tool 1 is used. .

(Production method)
In order to manufacture the above-described surface-coated cutting tool, first, the above-described tungsten carbide base cemented carbide base material can be formed by firing, WC, 4a, 5a, 6a group metal carbide, nitride, carbonitride, etc. Co and other metal powders, carbon powder, etc. are appropriately added to and mixed with the inorganic powder, and formed into a predetermined tool shape by a known forming method such as press molding, cast molding, extrusion molding, cold isostatic pressing, etc. After that, the above-described tungsten carbide base cemented carbide base material is manufactured by firing in a vacuum or in a non-oxidizing atmosphere.

  Then, after polishing the base material as desired, a hard coating layer is formed on the surface by chemical vapor deposition. The film forming conditions for each layer are shown below.

For example, a nitride of titanium, carbide, carbonitride, the first layer 2 forming a film composed of a single layer and or layers of carbon nitride, 0.1～10Vol the TiCl ₄ gas in volume percent as a reaction gas composition %, 0~60vol% _{N 2} gas, 0～0.1Vol% of CH ₄ gas, 0～0.1Vol% of _CH 3 CN gas, 0～0.1Vol% CO ₂ gas, and the remainder _{H 2} gas The mixed gas consisting of is sequentially introduced into the reaction chamber, and the inside of the chamber is formed at 800 to 1100 ° C. and 5 to 85 kPa.

Among them, the conditions for forming the stripe-shaped TiCN layer, as a reaction gas composition, 0.1～10Vol% of TiCl ₄ gas by volume%, 0~60vol% _{N 2} gas, a CH ₄ gas 0-0 .1 vol%, CH ₃ CN gas 0 to 0.1 vol%, and the remaining gas mixture consisting of H ₂ gas are sequentially adjusted and introduced into the reaction chamber, and the chamber is made at 700 to 900 ° C. and 5 to 85 kPa. Film.

Subsequently, in the formation of the third layer 4 made of aluminum oxide, ₃ to 20 vol% of AlCl ₃ gas, 0.5 to 3.5 vol% of HCl gas, 0 to 0.01 vol% of H ₂ S gas, and the rest Film formation is performed under conditions of 900 to 1100 ° C. and 5 to 10 kPa using a mixed gas composed of H ₂ gas.

  According to the present invention, after the first layer 2 and the third layer 4 are sequentially formed, the processing temperature is maintained at 850 to 1100 ° C. for 1 to 10 hours in a hydrogen and / or nitrogen atmosphere of 1 to 40 kPa. The main feature is that heat treatment is performed, whereby the second layer 3 can be formed by diffusion from the base material 6, the first layer 2, and the third layer 3.

Then, if necessary, a TiN film is formed as the outermost layer 5 for use corner identification. Conditions for forming the TiN layer is the outermost layer 5, 0.1～10Vol% of the TiCl ₄ gas, 20～60Vol% _{N 2} gas, a mixed gas balance being _{H 2} gas, 800 to 1100 ° C., The outermost TiN layer is coated under the condition of 50 to 90 kPa.

The film thickness of each layer can be controlled by the film formation time in addition to the above conditions.

  8.0% by weight of metallic cobalt (Co) powder with an average particle size of 1.2 μm, 0.7% by weight of tantalum carbide (TaC) with an average particle size of 2.0 μm, 0.6% by weight of titanium carbide, niobium carbide Was formed into a cutting tool shape (CNMA120204) by press molding, and then subjected to binder removal treatment, and further, 0.4% by weight, and the balance consisting of tungsten carbide (WC) powder having an average particle size of 1.5 μm as a balance. The temperature was increased at a rate of 1000 ° C. or higher at a rate of 3 ° C./min and fired in a vacuum of 0.01 Pa at 1500 ° C. for 1 hour to prepare a tungsten carbide base cemented carbide base material.

  A cutting tool composed of a hard coating layer having the structure shown in Table 1 was prepared on the surface of the obtained tungsten carbide-based cemented carbide base material by a CVD method.

In the method of forming the hard coating layer, the TiN of the first layer and the outermost layer uses a mixed gas composed of 5% by volume of TiCl ₄ gas, 45% by volume of N ₂ gas, and the remainder of H ₂ gas at 1000 ° C. , 70 kPa.

The first layer of TiC was formed in an atmosphere of 1000 ° C. and 70 kPa using a mixed gas composed of 5% by volume of TiCl ₄ gas, 0.05% by volume of CH ₄ gas, and the remaining H ₂ gas.

The first layer of TiCN is 5% by volume of TiCl ₄ gas, 40% by volume of N ₂ gas, 0.05% by volume of CH ₄ gas, 0.07% by volume of CH ₃ CN gas, and the remainder from H ₂ gas. The resulting mixed gas was deposited in an atmosphere of 800 ° C. and 65 kPa.

The third layer of Al ₂ O ₃ is 10% by volume of AlCl ₃ gas, 1.5% by volume of HCl gas, 1.5% by volume of CO ₂ gas, 0.01% by volume of H ₂ S gas, and the rest Film formation was performed in an atmosphere of 1000 ° C. and 7 kPa using a mixed gas composed of H ₂ gas.

  Further, in Sample Nos. 1 to 5, after the third layer made of aluminum oxide was formed, heat treatment was performed under the conditions shown in Table 2 to produce a second layer.

  In Sample No. 7, after the first layer made of a titanium compound was formed, heat treatment was performed for 2 hours in a furnace having a temperature of 1000 ° C., a pressure of 20 kPa, and a hydrogen atmosphere.

With respect to the obtained surface-coated cutting tool, the fracture surface of the hard coating layer was observed with a scanning electron microscope, and the film thickness of each layer was measured. The apparatus used was a scanning electron microscope manufactured by Hitachi S800. Further, the composition of the second layer was measured by Auger electron spectroscopic analysis at the fracture surface (point A in FIG. 2). An example of the analysis result is shown in FIG. Table 1 shows the peak intensity ratio of 400 eV Ti with respect to the Al peak intensity near 1400 eV. Further, when the peak intensity of Al near 1400 eV, the peak intensity of W near 1750 eV, and the peak intensity of Co near 800 eV measured by Auger electron spectroscopic analysis are I _Al , I _W , and I _Co , The I _W / I _Al ratio was calculated and shown in Table 1. The apparatus used for the Auger electron spectroscopy analysis here is a PHI Model 680 scanning FE-Auger electron spectroscopy analyzer. The crystal structure of the aluminum oxide layer was performed using general X-ray diffraction analysis. The results are shown in Table 1. Here, the apparatus used for the X-ray diffraction analysis is RINT1100 manufactured by Rigaku Corporation.

  Further, as a result of analyzing the W and Co concentrations in the cross section of the sample by EDS analysis, the sample No. In 1 to 5, the W and Co concentrations in the vicinity of the extreme surface of the base material were high, and the W and Co concentrations in the second layer were twice or more higher than those in the first layer and the third layer. On the other hand, sample No. In 6 and 7, W and Co were not detected in the hard layer. In Sample No. 7 in which heat treatment was applied after the first layer was formed, the formation of the second layer was not observed, and W and Co were detected in the first layer.

  Then, using this cutting tool, cast iron was cut under the following conditions, the cutting edge of the cutting tool was observed, and the amount of flank wear was measured. In addition, the cutting time when the amount of flank wear reached 0.2 mm during the cutting test was measured. Furthermore, a chipping resistance test and a film peeling resistance test were performed by cutting a cast with black skin, and the ratio of the number of corners chipped and peeled when 20 corners were evaluated was compared. The closer to 0, the better the performance, and the closer to 100, the worse the performance. These results are shown in Table 1.

(Abrasion resistance test)
Work material: Cast iron with black skin (FC250)
Tool shape: CNMA120204
Cutting speed: 350 m / min Feeding speed: 0.4 mm / rev
Cutting depth: 1.0mm
Others: Solution-based water-soluble cutting fluid used (chipping resistance test)
Work material: Cast iron with black skin (FC250)
Tool shape: CNMA120204
Cutting speed: 350 m / min Feeding speed: 0.4 mm / rev
Cutting depth: 1.0mm
Others: Solution-based water-soluble cutting fluid used (film peeling test)
Work material: Cast iron with black skin (FC250)
Tool shape: CNMA120204
Cutting speed: 350 m / min Feeding speed: 0.3 mm / rev
Cutting depth: 4.0mm
Others: Uses water-based cutting fluid

  From Table 1, sample No. 1 provided with a second layer containing Al, Ti, W, Co. In Nos. 1 to 5, both the peel resistance and chipping resistance by the cutting test were good results, and excellent wear resistance was exhibited.

  On the other hand, Sample No. 6 in which the second layer was not provided had poor wear resistance, peel resistance, and chipping resistance.

  In Sample No. 7, which was heat-treated after the first layer made of a titanium compound was formed, film peeling, particularly peeling of the aluminum oxide layer occurred, and the chipping resistance and wear resistance were not sufficient. It was.

It is a conceptual diagram showing an example about the structure of the hard coating film of the surface coating cutting tool in this invention. It is a mimetic diagram about the 2nd layer neighborhood of the surface covering cutting tool in the present invention. It is a schematic diagram about the base material interface (underlayer) of the surface-coated cutting tool in the present invention. It is an Auger electron spectroscopy analysis result in the 2nd layer (point A) of the surface coating cutting tool (FIG. 2) of this invention.

Explanation of symbols

1 hard layer 2 first layer 3 of tungsten by the second layer 4 third layer 5 outermost 6 preform 7 peak value I _W Auger electron spectroscopic analysis of aluminum by the lowermost 8 uppermost 9 intermittent part I _Al Auger electron spectroscopy points analyzed for peak value a Auger electron spectroscopy cobalt by peak value I _Co Auger electron spectroscopic analysis of the

Claims (10)

On the surface of the tungsten carbide base cemented carbide base material, a first layer composed of a single layer or multiple layers of titanium nitride, carbide, carbonitride, carbonitride, and at least titanium (Ti), aluminum (Al ), A hard coating layer formed by sequentially forming a second layer mainly containing tungsten (W) and cobalt (Co) and a third layer made of aluminum oxide , and the second layer is intermittently present. And an average film thickness when the second layer is assumed to be continuous and uniformly present is 0.05 to 4 μm . 2. The surface-coated cutting tool according to claim 1, wherein the second layer is formed by diffusion of any element in the base material, the first layer, and the third layer. . In the Auger electron spectroscopic analysis data for the second layer, when the peak intensity of Al near 1400 eV, the peak intensity of W near 1750 eV, and the peak intensity of Co near 800 eV are IAl, IW and ICo, respectively, IW / IAI The surface-coated cutting tool according to claim 1 or 2 , wherein = 0.1 to 0.5 and ICo / IAl = 0.1 to 0.5. The surface-coated cutting tool according to any one of claims 1 to 3 top layer is characterized by comprising a stripe-shaped titanium carbonitride layer of said first layer. The surface-coated cutting tool according to claim 4, wherein an average film thickness of the streaky titanium carbonitride layer is 0.5 to 15 μm. 6. The surface-coated cutting tool according to claim 4, wherein the lowermost layer of the first layer is made of a granular titanium nitride layer. The surface-coated cutting tool according to claim 6, wherein an average film thickness of the titanium nitride layer is 0.5 to 3 μm. It said third layer of aluminum oxide is κ-type crystals, or κ-type crystal accounts for more than 50 wt%, according to any one of claims 1 to 4, characterized in that the rest is composed of a mixed crystal consisting of α-type crystals Surface coated cutting tool. The surface-coated cutting tool according to any one of claims 1 to 8 , wherein a concentration of W and Co on the extreme surface of the tungsten carbide base cemented carbide base material is higher than that in the base material. . 3. The surface according to claim 1, wherein the W and Co concentrations in the second layer are twice or more higher than the W and Co concentrations in the first layer and the third layer. Coated cutting tool.

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